Motivation and emotion/Book/2014/Reticular formation, arousal and emotion

Reticular formation, arousal, and emotion:
What role does the reticular formation play in arousal and emotion?

Multimedia presentation (5 min)

Overview

The reticular formation's role in arousal and emotion is a multidimensional and overlapping one with the three structures being interconnected with one another (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968). This interconnection causes a chain reaction starting from the reticular formation, moving to arousal levels, and concluding with emotion (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968). That is, the reticular formation produces and maintain arousal levels which have an affect of the experience of emotion. In order to understand how the reticular formation contributes to arousal and emotion, it first needs to be understood what the individual roles and functions of the three structures are. The reticular formation is located within the brain stem and activates and maintains arousal levels (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968) and is also interconnected with the limbic system and cerebral cortex (regions also associated with emotions, Mitterauer, 2014; Snell, 2009). Arousal is a multidimensional construct that has a role in the processing of the body's levels of alertness and wakefulness (Anderson, 1990). And finally, emotions are multidimensional constructs thought to be made up of subjective, biological, purposive, and social constructs that work together to create in an overall expressed and experienced emotion (Borod, 1993; Izard, 1993). Understanding these structures individually will aid in understanding the reticular formation's role in arousal and emotion.

Reticular formation

Figure 1. Reticular formation located within the brain stem

What is it?

The reticular formation was first described by Moruzzi and Magoun (1949, as cited in Routtenberg, 1968) who found that it was associated with the midbrain and hindbrain which is capable of activating and arousing the cerebral cortex. Furthermore, it is a system that activates and maintains an organism's arousal levels (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968) and it also organizes and provides the reaction responses for the organism (Routtenberg, 1968). The reticular formation is a cluster and network of nerve cells and nerve fibres throughout the brain stem that connects the motor (descending pathway) and sensory nerves (ascending pathway) to and from the spinal cord, cerebellum, and cerebrum (Snell, 2009; Spilman, 2003).

Purpose

Research has indicated that the reticular formation is important and has a vital role in numerous psychological (Samuels, 1959) and physiological (Mitterauer, 2014) functions. It is also interconnected with other brain regions, particularly with the limbic system and cerebral cortex (Mitterauer, 2014). It is also focused on individuals' responses to situations and events, as these responses are important regarding the type of reinforcement received (Routtenberg, 1968). For example, Routtenberg (1968) indicates that approach responses are positively reinforced and withdrawal responses are negatively reinforced. However, he also indicates that the reticular formation needs to be active in order for the individual to select responses appropriate for the desired reinforcement.

Functions

The reticular formation has seven functions (Snell, 2009), including two pathways to and from the brain stem: ascending and descending pathways (Snell, 2009; Spilman, 2003):

1. Control of skeletal muscles: can influence the activity of alpha and gamma motor neurons, resulting in the reticular formation being able to exert some control over muscle tone and reflex activity;
2. Control of somatic and visceral sensations: has a facilitative and inhibitory influence on ascending pathways to the brain, and plays a role in controlling the perception of pain;
3. Control of the autonomic nervous system: has control of the cerebral cortex, hypothalamus, and other subcortical features of the autonomic nervous system;
4. Control of the endocrine nervous system: the ability to either directly or indirectly influence the production or release of either releasing or release-inhibiting factors;
5. Influence on the biological clocks: potential influence towards the body's biological rhythms via its pathways to the hypothalamus;
6. Ascending pathway: connects sensory nerves to and from the spinal cord, cerebellum, and cerebrum; and,
7. Descending pathway: connects motor nerves to and from the spinal cord, cerebellum, and cerebrum.

Ascending pathway

The level of consciousness and arousal that an individual feels and expresses is controlled by the sensory information carried by the ascending pathway to the reticular formation, with the degree and extent of consciousness and wakefulness being dependent upon the continuous level of sensory activity that is carried by the ascending pathway to the reticular formation, which then delivers the sensory information to the cerebral cortex (Snell, 2009; Spilman, 2003).

The ascending pathway also relays the information of sensory stimuli from all the different sensory pathways of the body, through the ascending fibres, to the thalamus which relays the sensory information to the cerebral cortex (Snell, 2009; Spilman, 2003). These sensory stimuli include proprioception (sense of where one's body is in terms of their position, motion, and equilibrium (balance)), touch, pain, temperature, visual, and auditory (Spilman, 2003).

Descending pathway

The descending pathway plays a vital role in visceral and somatic activities and sensations, and does this in two ways:

1. from the hypothalamus it carries and passes impulses and sensations to the automatic nervous system and various bodily organs, and,
2. from the subcortical motor areas it carries and passes on impulses and sensations to voluntary muscles (Spilman, 2003).

The descending pathway also plays a role in posture and regulating general muscle tone (Reeve, 2009; Spilman, 2003). There are a number of autonomic features that the descending pathway has control and influence over including: gland secretion, the bladder, respiratory and cardiovascular systems, swallowing, and vomiting reflexes (Spilman, 2003).

Practical look

The reticular formation has the ability to generate forms of behaviour (sleeping, eating) and can control and direct behaviour in accordance with environmental information (Mitterauer, 2014). Put simply, the reticular formation can create behaviours based on the information presented and obtained from the surrounding environment.

Figure 2. Sleeping: inactive reticular formation

Sleeping is considered to be a passive process that supposedly results from the reduction of sensory input into the reticular formation which then leads to the structure's inactivity (Routtenberg, 1966) and lack of responsiveness (Routtenberg, 1968). Furthermore, the reticular formation is either active (wakefulness, arousal) or inactive (sleep) (Routtenberg, 1966). An example of the reticular formation in action can be seen in an explanation by Samuels (1959).

Figure 3. Aroused cat: active reticular formation

Samuels (1959) explained that at low levels of stimulation and arousal, a sleeping animal would open its eyes and begin to react to surrounding auditory and visual stimuli. With slightly higher levels of stimulation and arousal, the animal wakes up and scans its surroundings. With further increases of stimulation and arousal, the animal would be abruptly aroused resulting in typical animal tendencies of holding still, start to experience flight (flight-or-fight response), fear, agitation at the situation, and finally the frantic efforts to escape the situation.

Arousal

What is arousal?

Arousal is a multidimensional construct comprised of three processes that play a role in the body's alertness, wakefulness, and activation, with each process contributing a different function and aspect of the human body and it is the activity of these processes that make up the overall construct of arousal (Anderson, 1990). These three processes, according to Anderson (1990), are cortical (brain), behavioural (skeletal muscular system), and autonomic (autonomic nervous system), and it is the combined activity of these three processes that make up and constitute the construct of arousal.

Principles of arousal

There are four principles that can explain the contribution of arousal to emotion and emotional states (Reeve, 2009):

1. An individual's level of arousal is mostly a function of how stimulating their surrounding is;
2. Individuals engage and partake in behaviours in order to either increase or decrease their levels of arousal;
3. Underarousal: individuals will seek out opportunities within their environment that will increase their arousal levels due to environmental stimulation increases being pleasurable and performance-enhancing whereas environmental stimulation decreases are considered to be aversive (unpleasant and needing to avoid) and undermine and weaken performance; and,
4. Overarousal: individuals will seek out opportunities within their environment that will decrease their arousal levels due to environmental stimulation increases being considered aversive (unpleasant and needing to avoid) and undermine performance, whereas, environmental stimulation decreases are considered to be pleasurable and performance enhancing.

It is the various combinations of these four principles of arousal that can help to understand and explain the effect that arousal has on individuals' ensuing emotions and emotional states (Reeve, 2009). Furthermore, the third principle, underarousal, has been linked to some studies (Geiwitz, 1966; London, Schubert, & Washburn, 1972) in regards to the effects of boredom on arousal.

Arousal and boredom

The experience of boredom is composed of four structures, and is studied in relation to these structures: arousal, constraint, subjective repetitiveness, and unpleasantness (Geiwitz, 1966). Thus, the experience of intense boredom, resulting from repetition of easy and mundane tasks, is associated with decreased, or under, arousal and increased constraint, task repetitiveness, and experiences of unpleasantness (i.e. feelings of unpleasantness, emotional discomfort).

Figure 4. Boredom

To determine these changes and interactions among the four structures, Geiwitz (1966) conducted four experiments that assessed and manipulated boredom and its effects. The results of all four experiments came to a common consensus with participants' reporting of boredom being associated with low levels of arousal (underarousal) and/or increased feelings of unpleasantness (emotional distress and discomfort), constraint, and task and movement repetitiveness (Geiwitz, 1966). Furthermore, he also found that boredom can be produced solely by decreasing and creating underaroused levels or by increasing one of the other factors. Geiwitz's (1966) findings suggest that boredom can result from two factors, by either

1. creating an environment that is low in stimulation and interest to the individual resulting in decreased arousal levels, or
2. increasing the feelings of unpleasantness (increasing emotional distress and discomfort), constraint, and the repetition of an easy and mundane task.

Similar to Geiwitz's (1966) findings are those of London, Schubert, and Washburn (1972) who found that boredom increases autonomic arousal (i.e., feelings of anxiety and emotional distress or unpleasantness). Furthermore, they also found that when individuals are required and made to focus their attention on tasks and activities that are perceived and considered to be boring and too easy to do and complete, the individual will experience increases in feelings of anxiety and emotional distress and unpleasantness (increased autonomic arousal).

Arousal and emotion

The interplay of arousal and emotion has been examined through emotion regulation and arousal (Shepherd & Wild, 2014), using arousal as a determinant of emotion (Goldstein, Fink, & Mettee, 1972), and the effects of arousal on hemispheric emotion (emotion activation in each hemisphere, Zhang, Zhou, & Oei, 2011).

Emotion Regulation and Arousal

Shepherd and Wild (2014) examined the interplay between regulating emotions and arousal by examining the regulating of negative emotions of trauma-exposed individuals (paramedics) with post-traumatic stress disorder (PTSD) symptoms on their arousal levels.

They had trauma-exposed individuals rate their trauma experiences, PTSD symptoms, and emotion intensity when exposed to negative and unpleasant images. Arousal levels were recorded and monitored electronically. They also had the participants enhance, decrease, or maintain their negative emotions when responding to the images.

Results found that when exposed to each emotion regulation condition, the participants' arousal levels decreased. Furthermore, it was also found that arousal levels provide a more reliable and accurate indication and measure of an individual's ability to regulate their emotions, compared to self-report measures (Shepherd & Wild, 2014).

Shepherd and Wild's (2014) findings seem to suggest and imply that when exposed to negative and unpleasant images, individuals who have had repeated exposure to traumatic or negative events or circumstances (i.e. paramedics), can (potentially) regulate their emotions rather well, and possibly better than individuals who do not experience traumatic or negative events regularly, and in turn can maintain decreased or low levels of arousal in response to the event.

Arousal as a determinant of emotion

The idea that emotions can be determined by arousal levels was examined by Goldstein, Fink, and Mettee (1972). They looked at how arousal levels impacted on reported emotional states.

They had participants view images of same and different sex nudes, and had their arousal levels monitored (in this case heart rate changes) at the same time. Participants also reported their level of emotion for each imaged viewed.

Results indicated that participants reported their emotional levels and states when their arousal levels changed (changes in heart rate). Furthermore, Goldstein et al's. (1972) findings further indicated that the more arousal the images created, the more intense their emotions were reported as being. An explanation for this was offered by Schachter and Singer (1962, as cited in Goldstein et al., 1972), who also looked at arousal as a determinant of emotion, which explains that individuals will experience and express emotions and emotional states in accordance with, and only to, the extent that arousal is experienced and present.

It can be implied from Goldstein et al.'s. (1972) findings that emotional states will have a higher and more successful chance of being experienced and expressed when arousal levels are also experienced. That is, no or little arousal will result in no or little emotions to the situation. Thus, it can be seen that emotions are a by-product of corresponding arousal levels. |}

Arousal and hemispheric emotion

Just as the use and constructs of logic and creativity are left or right brain hemisphere dominant, so too are emotions, particularly emotion perceptions and experiences (Zhang et al., 2011). This idea and concept of emotion hemispheric dominance was studied by Zhang, Zhou, and Oei (2011) and is referred to as hemispheric asymmetry of emotion, characterized by stronger and more intense brain activity in one hemisphere than in the other (similar to how logic and creativity activate more activity in one hemisphere than the other). Furthermore, they found that an individual's level of arousal, either high or low, plays a role in the activation for the emotion perspective and experience in one hemisphere over the other. That is, arousal levels, high or low, partake in activating emotional responses in each hemisphere.

Zhang et al. (2011) studied the concept of hemispheric asymmetry of emotion by having participants view different multiple sequences of images relating to emotional perception and experience, with hemispheric activity recoded and monitored electronically.

Results indicated that viewing images that evoked high arousal levels prompted stronger and more intense emotional activation in the right hemisphere, whilst viewing images that evoked low arousal levels prompted stronger and more intense emotional activation in the left hemisphere (Zhang et al., 2011). The level of arousal needed to active emotion in one hemisphere over the other could be due to the way each hemisphere processes and responds to emotional information, with the right hemisphere focusing on how an individual is feeling (understanding the situation), with the left focusing on what the individual is feeling (gives a label or name to the feeling, American Psychological Association [APA], 2014).

Zhang et al.'s. (2011) findings can imply that the degree and intensity to which an individual's emotional perception and experience of an event or image is, is determined by how little or how much an individual is aroused, which in turn activates one's emotion dominate based on the experienced level of arousal. That is, the individual will either focus on the how the situation is making them feel (right hemisphere), or will focus on the experienced emotion itself (left hemisphere).

Emotion

Figure 5. Emotions work together, like a puzzle

What is emotion?

Emotions are multidimensional constructs that have both cognitive and non-cognitive elicitors (Izard, 1993), and these constructs are thought to be made up of a number of factors that use different brain systems and functions (Borod, 1993). There are four constructs that emotions are said to be built upon (Izard, 1993; Plutchik, 1984, as cited in Borod, 1993), with each construct having and creating its own mark and effect on the resulting overall expressed emotion:

• subjective: subjective feelings - makes the individual feel a particular way;
• biological: biological reactions - energy-mobilising responses that prepare the body for adapting to situations;
• purposive: agents of purpose - like hunger has a purpose; and,
• social phenomena: individuals communication with eachother through facial, postural, and vocal signs and language.

The multiple dimensions of emotions work together to result in an overall emotion that is the product of a significant life-event or experience of an individual (Izard, 1993; Lazarus, 1991a). Thus, the emotion generated is in response to the individual's level of cognitive activity, and it is this cognitive activity that creates meaning and some form of understanding for the individual regarding the life-event or experience (Lazarus, 1991a). In other words, when an individual encounters a significant life-event or experience, they experience an emotional response to that life-event or experience. The emotional response experienced is created in response to the level of cognitive activity the individual develops in order to understand and make meaning of the encountered life-event or experience.

Types of emotions

There are considered to be two forms of emotions; discrete and higher order emotions. According to Borod (1993) discrete emotions are those that are seen as the building blocks that underlie and make up the higher order forms of emotions such as, guilt, outrage, and joy.

Figure 6. Basic and higher order emotions

Discrete emotions are emotions that appear to be biologically based, universal, and cross cultural, that is, the emotions appear in similar circumstances and situations across cultures, and are also known as basic emotions (Borod, 1993). According to Ekman and Friesen (1975, as cited in Borod, 1993) the basic emotions include happiness, surprise, sadness, anger, fear, and disgust, with Izard (1971, as cited in Borod, 1993) further including interest and shame. It is from these basic emotions that the higher order forms of emotions are developed (Borod, 1993).

Figure 7. Emotional expression with others

Functions of emotions

There is a widespread consensus on the purpose and functions of emotions, regardless of how they are expressed and interpreted (Parrott, 2001). The consensus suggests that emotions are adaptive and useful to and for the individual (Keltner & Kring, 1998; Lazarus, 1991b; Parrott, 2001). Furthermore, emotions function as a tool for knowing how and why an individual needs to respond and adapt to events and circumstances experienced throughout life (Parrott, 2001).

Social-Functional Approach

Keltner and Kring (1998) suggested that emotions help individuals to coordinate and organize their daily social interactions, which is said to help individuals to create and maintain relationships that are beneficial to and for themselves. Furthermore, they (1998) indicate that an individual's expression and experiences of emotions provides fellow individuals with information regarding their own intentions, wellbeing, surrounding environment, and the circumstances and conditions of their social relations with others. In other words, the manner in which an individual expresses and experiences emotions provides surrounding individuals with information pertaining to the sender's state of mind and position in relation to their own intentions, wellbeing, and relationships with others.

Predictability and dependability of emotions

Lazarus (1991b) suggests that emotions are predictable and dependent on individuals' social constructions and relationships, along with the meanings and reasoning individuals use to explain and understand what is considered to be harmful and of benefit to themselves. The social constructions and meanings individuals provide requires the use of the individuals' judgments, their ability to learn from past experiences and situations, and to be able to differentiate between differences that demonstrate different consequences and outcomes for one's wellbeing (Lazarus, 1991b). Thus, Lazarus' (1991b) findings can imply that emotions can and will be repeated if an individual is in the presence of their regular social relationships, and that the experiences an individual encountered with the expressed emotions should make it easier for an individual to make better and more beneficial outcomes the next time round. |}

Putting it altogether

The reticular formation is associated with the production of both arousal and emotion (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968). It's role in the two overlap and causes a chain reaction in that the reticular formation activates arousal levels which then has an effect on emotion activation (Mitterauer, 2014). That is, it activates and maintains arousal levels which, in turn, activates emotions and emotional states and responses: arousal levels affect the arousal and activation of emotion and emotional responses.

As the reticular formation becomes active (i.e., waking, consciousness, Routtenberg, 1966; Snell, 2009) it starts activating and increasing arousal levels (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968). These arousal levels continue to increase with every stimulation increase the reticular formation receives from the environment (Samuels, 1959). As the reticular formation becomes more active, it activates and arouses the limbic system and cerebral cortex (brain structures also associated with emotion, Mitterauer, 2014). Due to its connections with the limbic system and cerebral cortex (Mitterauer, 2014), the reticular formation has an influential effect and control over the reactions and responses of those two regions (Samuels, 1959; Snell, 2009). That is, the reticular formation controls and influences the level of arousal the limbic system and cerebral cortex receive, thus affecting the level of emotional response.

When the reticular formation is overaroused, resulting in high levels of arousal throughout the body and to the limbic system and cerebral cortex, the individual will begin to experience feelings of unpleasantness and emotional distress and discomfort (Reeve, 2009; Samuels, 1959). As was demonstrated in Samuels' (1959) explanation of the overaroused cat that began to feel discomfort, agitation, and fear.

A process similar to this can be seen in the effects of underarousal. When the reticular formation is becoming less active, but not to the point of inactivity (i.e., sleep), there is less arousal activity to the limbic system and cerebral cortex (Routtenberg, 1966; Snell, 2009). It is this inactivity and low arousal levels that causes the individual to experience feelings of unpleasantness and emotional distress and discomfort (Reeve, 2009). As was demonstrated in Geiwitz' (1966) experiment on boredom and arousal where the participants began to experience unpleasant feelings and emotional distress due to a lack of arousal from the repetitiveness nature of the mundane and easy tasks.

Individuals will either seek out stimulation that decreases (when overaroused) or increases (when underaroused) arousal levels, resulting in pleasurable feelings and emotional comfort (Reeve, 2009; Samuels, 1959). There needs to be a balance in the level of arousal produced and maintained by the reticular formation (Mitterauer, 2014; Reeve, 2009; Routtenberg, 1968). The balance in arousal will ensure feelings of pleasure and emotional comfort (Reeve, 2009), as individuals do not like feelings of unpleasantness and emotional discomfort and distress (Reeve, 2009).

See also

• Emotion (Book chapter, 2010)
• Arousal (Book chapter, 2010)
• Emotion and human interaction (Book chapter, 2013)
• Nature and emotion (Book chapter, 2013)
• |Arousal
• |Reticular formation
• |Emotion

References

American Psychological Association (APA) (2014). Both halves of brain process emotional speech. Retrieved from http://www.apa.org/monitor/apr03/brain.aspx

Anderson, K. J. (1990). Arousal and the inverted-U hypothesis: A critique of Neiss's 'Reconceptualizing arousal.'. Psychological Bulletin, 107(1), 96-100. doi:10.1037/0033-2909.107.1.96

Borod, J. C. (1993). Emotion and the brain—anatomy and theory: An introduction to the Special Section. Neuropsychology, 7(4), 427-432. doi:10.1037/0894-4105.7.4.427

Geiwitz, P. (1966). Structure of boredom. Journal Of Personality And Social Psychology, 3(5), 592-600. doi:10.1037/h0023202

Goldstein, D., Fink, D., & Mettee, D. R. (1972). Cognition of arousal and actual arousal as determinants of emotion. Journal Of Personality And Social Psychology, 21(1), 41-51. doi:10.1037/h0031873

Izard, C. E. (1993). Four systems for emotion activation: Cognitive and noncognitive processes. Psychological Review, 100(1), 68-90. doi:10.1037/0033-295X.100.1.68

Keltner, D., & Kring, A. M. (1998). Emotion, social function, and psychopathology. Review Of General Psychology, 2(3), 320-342. doi:10.1037/1089-2680.2.3.320

Lazarus, R. S. (1991a). Cognition and motivation in emotion. American Psychologist, 46(4), 352-367. doi:10.1037/0003-066X.46.4.352

Lazarus, R. S. (1991b). Progress on a cognitive-motivational-relational theory of emotion. American Psychologist, 46(8), 819-834. doi:10.1037/0003-066X.46.8.819

London, H., Schubert, D. S., & Washburn, D. (1972). Increase of autonomic arousal by boredom. Journal Of Abnormal Psychology, 80(1), 29-36. doi:10.1037/h0033311

Mitterauer, B. J. (2014). Model of the reticular formation of the brainstem based on glial–neuronal interactions. Cognitive Computation, doi:10.1007/s12559-014-9260-5 Retrieved from http://zh9bf5sp6t.search.serialssolutions.com.ezproxy.canberra.edu.au/?genre=article&issn=18669956&title=Model%20of%20the%20reticular%20formation%20of%20the%20brainstem%20based%20on%20glial%2013neuronal%20interactions.&volume=&issue=&date=20140603&atitle=Model%20of%20the%20reticular%20formation%20of%20the%20brainstem%20based%20on%20glial%E2%80%93neuronal%20interactions.&spage=&pages=&sid=EBSCO:PsycINFO&au=Mitterauer,%20Bernhard%20J

Parrott, W. (2001). Implications of dysfunctional emotions for understanding how emotions function. Review Of General Psychology, 5(3), 180-186. doi:10.1037/1089-2680.5.3.180

Reeve, J. (2009). Understanding Motivation and Emotion (5th Ed.). Hoboken, NJ: Wiley

ROUTTENBERG, A. (1966). NEURAL MECHANISMS OF SLEEP: CHANGING VIEW OF RETICULAR FORMATION FUNCTION. Psychological Review, 73(6), 481-499. doi:10.1037/h0023889

ROUTTENBERG, A. (1968). THE TWO-AROUSAL HYPOTHESIS: RETICULAR FORMATION AND LIMBIC SYSTEM. Psychological Review, 75(1), 51-80. doi:10.1037/h0025303

Samuels, I. (1959). Reticular mechanisms and behavior. Psychological Bulletin, 56(1), 1-25. doi:10.1037/h0044488

Shepherd, L., & Wild, J. (2014). Emotion regulation, physiological arousal and PTSD symptoms in trauma-exposed individuals. Journal Of Behavior Therapy And Experimental Psychiatry, 45 (3), 360-367. doi:10.1016/j.jbtep.2014.03.002

Snell, R. S. (2009). Clinical Neuroanatomy (7th Ed.). Retrieved from https://www.inkling.com/read/clinical-neuroanatomy-snell-7th/chapter-9/reticular-formation

Spilman, B. (2003). Neurokinesiology: A New Path to Human Health. Retrieved from http://neurokinesiology.nuxit.net/Neurological_Background/the_reticular_formation.html

Zhang, J., Zhou, R., & Oei, T. S. (2011). The effects of valence and arousal on hemispheric asymmetry of emotion: Evidence from event-related potentials. Journal Of Psychophysiology, 25(2), 95-103. doi:10.1027/0269-8803/a000045

External Links

• Reticular formation further detailed
• Gait Guys' Dr Ivo Waerlop on the reticular formation
• Reticular activating system
• 5 natural emotions explanations
• Mapping emotions to the body